The present invention concerns a two step process for producing isobutylene from propylene and synthesis gas.
C.sub.4 -olefines have been used as starting materials for numerous petrochemical industrial processes. The greatest part of the total quantity of isobutylene and n-butylene is consumed in producing petrol components in so-called catalytic polymerizing or alkylation. However, both isobutylene and n-butylenes are being used ever more often as starting materials for various chemical compounds. Traditionally, butylene rubbers and polyisobutylene have been made from isobutylene. The demand for the compound has considerably increased in recent years, along with that for methylisobutylene ether (MTBE). The starting materials in the production of MTBE, which is an agent improving the octane number of petrol in great demand, are isobutylene and methanol. The demand for isobutylalcohol (TBA) has also increased for the same reason as that for MTBE. TBA is obtained from isobutylene upon hydration. Isobutylene is further consumed, for instance, in the manufacturing of tertiary butylphenols and butylcresols. of methylmethacrylate.
C.sub.4 -olefines are principally commercially produced by two different standard procedures: floating catalytic cracking (FCC), and steam cracking. In the first-noted process, petrol components are produced by cracking heavier crude oil fractions. In this connection, liquid petroleum gas fractions are formed as by-products, among others. Ethylene is the product in the latter process. In addition to the manufacturing as cracking products, it is possible to produce butylenes by dehydrogenating the equivalent paraffins. Dehydrogenation processes are expensive, with one of the essential limiting factors being the availability of the starting materials, above all that for isobutylene.